Thread: Kind of a Drag

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I'm not sure if the distributor still has a condenser or not. If it still has I didn't check that. Silly me.

Originally Posted by 36 sedan

OK, making progress, I assumed by the 12" of vacuum that you had a big cam in this motor. Now you say that when it's acting up you have a slight lope to it, now by this statement I'm assuming your motor is stock (or close to stock). So, vacuum should be much higher, more like 16-18", and with the carb whistle you probably have a vacuum leak. Check the vacuum plug caps at the the carb make sure they are all in place and good shape, and check the PCV & transmission hoses for cracks or splits.Curious is the trip up hill one direction?

Naw it's pretty level both ways. The motor has trw flat tops, the heads are World with 2.02 intakes and 1.60 exhausts. I think they're 72cc chambers not sure.550 springs.The cam is a hydraulic Lunati barebones, the middle offering. Maxes out at 5500 rpm although I can get 7000 rpm. At idle the vaccum is 14-13. Which is always that with that cam. The carb does have a whistle at idle which changes if I move the throttle around. If there's a vacuum leak it's hidden very nicely I checked everything vacuum except perhaps the vacuum advance. The carb is an Edelbrock 1406 600 cfm with jetting altered by a rejet kit. Worked beautifully. Intake is old Weiand hi rise dual plane. Valve train has hardened pushrods and roller rockers. I changed the rocker studs to longer ones. The timing chain is a true double roller indexed stock. Headers are flowtech ceramics. Exhaust is 2-.5 stainless with Flowmaster knock offs . Crossover pipe is a T.
Block is 030 over 4 bolt main fully studded with high volume oil pump and deep sump Miloden pan. Pistons have Molybdenum rings. walls were honed 600 crosshatch. The fuel pump is a Big End high volume mechanical with a regulator set at 5 PSI then splits to feed the carb and the gas side of the nitrous plate. I guess other than that the rest is stock. Everything worked great even drag racing.

I'm not aware of Hall effects needing a condenser for other than radio interference. Here's a few references to electronic ignition and other motor ills, note the ground reference problems..
http://www.wellsve.com/sft503/Counterpoint3_1.pdf
Electronic Ignition Overview
Breakerless Ignition

Thanks I got the all bookmarked.

I forgot to mention the carb is a stage and a half richer on both cruise and acceleration with .98 jets in the secondaries. Accelerator pump set to max on the linkage. Electrical choke slightly set to lean.

The HEI (chevy) do indeed have a capacitor.

The older ones are a metal can, the newer ones are a little rectangular, flat box, but located exactly where the old ones are, next to the module.

I'll try to dig up a thread where I replaced the one in the steaming turd.

Just for giggles, attach a wire to the distributor base and to a known good ground source, preferably directly to the battery ground and try it out. Distributors do not always ground well enough for electronics through their base (and/or the intake manifold). If this fixes it a perminate ground wire is in order

dang! I forgot the springs in the main metering. they're 7-in. Hg. I THINK!

Originally Posted by firebird77clone

The HEI (chevy) do indeed have a capacitor.

The older ones are a metal can, the newer ones are a little rectangular, flat box, but located exactly where the old ones are, next to the module.

I'll try to dig up a thread where I replaced the one in the steaming turd.

From Post #13 above the HEI is gone -

Originally Posted by Good Wrench

Ignition was changed a couple years ago with a fresh MSD distributor and a MSD Street fire ignition box. Distributor mechanical advance changed with a Moroso recurve kit. Vacuum advance is adjustable. No ignition in distributor just a connection to the hall effects switch.

Good idea on the ground, 36 sedan.

Well, the manifold is aluminum so not good grounding there. I'll check out the grounding on the distributor. Right now, i'd do a voodoo dance on the hood if it fixes it.

Basically the distributor just distributes. The spark chores are done by the ignition box although I guess I need to check ground on that. It's attached to a plastic inner fender well.

Originally Posted by firebird77clone

The HEI (chevy) do indeed have a capacitor.

No disrespect intended, but as I said, other than for radio suppression I don't believe the condenser (capacitor) is needed. However to your case, if a suppression capacitor shorts it will kill the ignition. I stand corrected, thank you.

Originally Posted by Good Wrench

Well, the manifold is aluminum so not good grounding there. I'll check out the grounding on the distributor. Right now, i'd do a voodoo dance on the hood if it fixes it.

Distributors usually have a gasket under their base, if the clamp is dirty it can be a poor ground and relying on spinning gears is never a good idea. I usually run a #8 ground wire from the ground on the block up to a intake manifold accessory bolt and continue it to the alternator ground lug, then use a #12 wire from there to the A/C compressor ground and distributor.

Well, i'll run a ground wire from the distributor clamp to the negative terminal on the battery although the distributor housing is aluminum as well. My distributor clamp is chrome.
So far what I need to do is re check distributor plate, vacuum advance, any condenser if it still has one, and ground the distributor and check ground on the ignition box. Am I missing anything else?

Yes, and you just reminded me. Is your MSD ignition box power and ground sourced directly from the battery, if not, change it so it is. This is very important and by itself can cause your problem.